SSMMapping - Cisco · ip igmp ssm-map static 11 172.16.8.11!!...! interface GigabitEthernet0/0/0 description Sample IGMP Interface Configuration for SSM-Mapping Example ip address

SSM Mapping

The Source Specific Multicast (SSM)Mapping feature extends the Cisco suite of SSM transition tools, whichalso includes URL Rendezvous Directory (URD) and Internet Group Management Protocol Version 3 Lite(IGMP v3lite). SSM mapping supports SSM transition in cases where neither URD nor IGMP v3lite isavailable, or when supporting SSM on the end system is impossible or unwanted due to administrative ortechnical reasons. SSM mapping enables you to leverage SSM for video delivery to legacy set-top boxes(STBs) that do not support IGMPv3 or for applications that do not take advantage of the IGMPv3 host stack.

• Finding Feature Information, on page 1• Prerequisites for SSM Mapping, on page 1• Restrictions for SSM Mapping, on page 2• Information About SSM Mapping, on page 2• How to Configure SSM Mapping, on page 6• Configuration Examples for SSM Mapping, on page 13• Additional References, on page 16• Feature Information for SSM Mapping, on page 17

Finding Feature InformationYour software release may not support all the features documented in this module. For the latest caveats andfeature information, see Bug Search Tool and the release notes for your platform and software release. Tofind information about the features documented in this module, and to see a list of the releases in which eachfeature is supported, see the feature information table.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support.To access Cisco Feature Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required.

Prerequisites for SSM MappingOne option available for using SSM mapping is to install it together with a Domain Name System (DNS)server to simplify administration of the SSM Mapping feature in larger deployments.

Before you can configure and use SSM mapping with DNS lookups, you need to add records to a runningDNS server. If you do not already have a DNS server running, you need to install one.

SSM Mapping1

Restrictions for SSM Mapping• The SSM Mapping feature does not share the benefit of full SSM. SSM mapping takes a group G joinfrom a host and identifies this group with an application associated with one or more sources, therefore,it can only support one such application per group G. Nevertheless, full SSM applications may still sharethe same group also used in SSM mapping.

• Enable IGMPv3 with care on the last hop router when you rely solely on SSM mapping as a transitionsolution for full SSM.

Information About SSM Mapping

SSM ComponentsSSM is a datagram delivery model that best supports one-to-many applications, also known as broadcastapplications. SSM is a core networking technology for the Cisco implementation of IP multicast solutionstargeted for audio and video broadcast application environments and is described in RFC 3569. The followingtwo components together support the implementation of SSM:

• Protocol Independent Multicast source-specific mode (PIM-SSM)

• Internet Group Management Protocol Version 3 (IGMPv3)

Protocol Independent Multicast (PIM) SSM, or PIM-SSM, is the routing protocol that supports theimplementation of SSM and is derived from PIM sparse mode (PIM-SM). IGMP is the Internet EngineeringTask Force (IETF) standards track protocol used for hosts to signal multicast group membership to routers.IGMP Version 3 supports source filtering, which is required for SSM. IGMP For SSM to run with IGMPv3,SSM must be supported in the router, the host where the application is running, and the application itself.

Benefits of Source Specific Multicast

IP Multicast Address Management Not Required

In the ISM service, applications must acquire a unique IP multicast group address because traffic distributionis based only on the IP multicast group address used. If two applications with different sources and receiversuse the same IP multicast group address, then receivers of both applications will receive traffic from thesenders of both applications. Even though the receivers, if programmed appropriately, can filter out theunwanted traffic, this situation would cause generally unacceptable levels of unwanted traffic.

Allocating a unique IPmulticast group address for an application is still a problem.Most short-lived applicationsuse mechanisms like Session Description Protocol (SDP) and Session Announcement Protocol (SAP) to geta random address, a solution that does not work well with a rising number of applications in the Internet. Thebest current solution for long-lived applications is described in RFC 2770, but this solution suffers from therestriction that each autonomous system is limited to only 255 usable IP multicast addresses.

In SSM, traffic from each source is forwarded between routers in the network independent of traffic fromother sources. Thus different sources can reuse multicast group addresses in the SSM range.

SSM Mapping2

SSM MappingRestrictions for SSM Mapping

Denial of Service Attacks from Unwanted Sources Inhibited

In SSM, multicast traffic from each individual source will be transported across the network only if it wasrequested (through IGMPv3, IGMP v3lite, or URD memberships) from a receiver. In contrast, ISM forwardstraffic from any active source sending to a multicast group to all receivers requesting that multicast group. InInternet broadcast applications, this ISM behavior is highly undesirable because it allows unwanted sourcesto easily disturb the actual Internet broadcast source by simply sending traffic to the same multicast group.This situation depletes bandwidth at the receiver side with unwanted traffic and thus disrupts the undisturbedreception of the Internet broadcast. In SSM, this type of denial of service (DoS) attack cannot be made bysimply sending traffic to a multicast group.

Easy to Install and Manage

SSM is easy to install and provision in a network because it does not require the network to maintain whichactive sources are sending to multicast groups. This requirement exists in ISM (with IGMPv1, IGMPv2, orIGMPv3).

The current standard solutions for ISM service are PIM-SM and MSDP. Rendezvous point (RP) managementin PIM-SM (including the necessity for Auto-RP or BSR) andMSDP is required only for the network to learnabout active sources. This management is not necessary in SSM, which makes SSM easier than ISM to installandmanage, and therefore easier than ISM to operationally scale in deployment. Another factor that contributesto the ease of installation of SSM is the fact that it can leverage preexisting PIM-SM networks and requiresonly the upgrade of last hop routers to support IGMPv3, IGMP v3lite, or URD.

Ideal for Internet Broadcast Applications

The three benefits previously described make SSM ideal for Internet broadcast-style applications for thefollowing reasons:

• The ability to provide Internet broadcast services through SSM without the need for unique IP multicastaddresses allows content providers to easily offer their service (IP multicast address allocation has beena serious problem for content providers in the past).

• The prevention against DoS attacks is an important factor for Internet broadcast services because, withtheir exposure to a large number of receivers, they are the most common targets for such attacks.

• The ease of installation and operation of SSM makes it ideal for network operators, especially in thosecases where content needs to be forwarded between multiple independent PIM domains (because thereis no need to manage MSDP for SSM between PIM domains).

SSM Transition SolutionsThe Cisco IOS suite of SSM transition solutions consists of the following transition solutions that enable theimmediate development and deployment of SSM services, without the need to wait for the availability of fullIGMPv3 support in host operating systems and SSM receiver applications:

• Internet Group Management Protocol Version 3 lite (IGMP v3lite)

• URL Rendezvous Directory (URD)

• SSM mapping

IGMP v3lite is a solution for application developers that allows immediate development of SSM receiverapplications switching to IGMPv3 as soon as it becomes available.

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SSM MappingSSM Transition Solutions

For more information about IGMP v3lite, see the “ Configuring Source Specific Multicast ” module.

URD is an SSM transition solution for content providers and content aggregators that allows them to deployreceiver applications that are not yet SSM enabled (through support for IGMPv3) by enabling the receivingapplications to be started and controlled through a web browser.

For more information about URD, see the see the “ Configuring Source Specific Multicast ” module.

SSM mapping supports SSM transition in cases where neither URD nor IGMP v3lite are available, or whensupporting SSM on the end system is impossible or unwanted due to administrative or technical reasons.

SSM Mapping OverviewSSM mapping supports SSM transition when supporting SSM on the end system is impossible or unwanteddue to administrative or technical reasons. Using SSM to deliver live streaming video to legacy STBs that donot support IGMPv3 is a typical application of SSM mapping.

In a typical STB deployment, each TV channel uses one separate IP multicast group and has one active serverhost sending the TV channel. A single server may of course send multiple TV channels, but each to a differentgroup. In this network environment, if a router receives an IGMPv1 or IGMPv2 membership report for aparticular group G, the report implicitly addresses the well-known TV server for the TV channel associatedwith the multicast group.

SSM mapping introduces a means for the last hop router to discover sources sending to groups. When SSMmapping is configured, if a router receives an IGMPv1 or IGMPv2 membership report for a particular groupG, the router translates this report into one or more (S, G) channel memberships for the well-known sourcesassociated with this group.

When the router receives an IGMPv1 or IGMPv2membership report for group G, the router uses SSMmappingto determine one or more source IP addresses for group G. SSM mapping then translates the membershipreport as an IGMPv3 report INCLUDE (G, [S1, G], [S2, G]...[Sn, G] and continues as if it had received anIGMPv3 report. The router then sends out PIM joins toward (S1, G) to (Sn, G) and continues to be joined tothese groups as long as it continues to receive the IGMPv1 or IGMPv2 membership reports and as long asthe SSM mapping for the group remains the same. SSM mapping, thus, enables you to leverage SSM forvideo delivery to legacy STBs that do not support IGMPv3 or for applications that do not take advantage ofthe IGMPv3 host stack.

SSM mapping enables the last hop router to determine the source addresses either by a statically configuredtable on the router or by consulting a DNS server. When the statically configured table is changed, or whenthe DNS mapping changes, the router will leave the current sources associated with the joined groups.

Static SSM MappingSSM static mapping enables you to configure the last hop router to use a static map to determine the sourcessending to groups. Static SSMmapping requires that you configure access lists (ACLs) to define group ranges.The groups permitted by those ACLs then can be mapped to sources using the ip igmp static ssm-map globalconfiguration command.

You can configure static SSM mapping in smaller networks when a DNS is not needed or to locally overrideDNS mappings that may be temporarily incorrect. When configured, static SSM mappings take precedenceover DNS mappings.

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SSM MappingSSM Mapping Overview

DNS-Based SSM MappingDNS-based SSM mapping enables you to configure the last hop router to perform a reverse DNS lookup todetermine sources sending to groups (see the figure below). When DNS-based SSM mapping is configured,the router constructs a domain name that includes the group address G and performs a reverse lookup into theDNS. The router looks up IP address resource records (IP A RRs) to be returned for this constructed domainname and uses the returned IP addresses as the source addresses associated with this group. SSM mappingsupports up to 20 sources for each group. The router joins all sources configured for a group.Figure 1: DNS-Based SSM-Mapping

The SSMmapping mechanism that enables the last hop router to join multiple sources for a group can be usedto provide source redundancy for a TV broadcast. In this context, the redundancy is provided by the last hoprouter using SSM mapping to join two video sources simultaneously for the same TV channel. However, toprevent the last hop router from duplicating the video traffic, it is necessary that the video sources utilize aserver-side switchover mechanism where one video source is active while the other backup video source ispassive. The passive source waits until an active source failure is detected before sending the video traffic forthe TV channel. The server-side switchover mechanism, thus, ensures that only one of the servers is activelysending the video traffic for the TV channel.

To look up one or more source addresses for a group G that includes G1, G2, G3, and G4, the following DNSresource records (RRs) must be configured on the DNS server:

IN A source-address-1G4.G3.G2.G1 [multicast-domain] [timeout]

IN A source-address-2

IN A source-address-n

The multicast-domain argument is a configurable DNS prefix. The default DNS prefix is in-addr.arpa. Youshould only use the default prefix when your installation is either separate from the internet or if the groupnames that you map are global scope group addresses (RFC 2770 type addresses that you configure for SSM)that you own.

The timeout argument configures the length of time for which the router performing SSMmapping will cachethe DNS lookup. This argument is optional and defaults to the timeout of the zone in which this entry isconfigured. The timeout indicates how long the router will keep the current mapping before querying the DNS

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SSM MappingDNS-Based SSM Mapping

server for this group. The timeout is derived from the cache time of the DNS RR entry and can be configuredfor each group/source entry on the DNS server. You can configure this time for larger values if you want tominimize the number of DNS queries generated by the router. Configure this time for a low value if you wantto be able to quickly update all routers with new source addresses.

Refer to your DNS server documentation for more information about configuring DNS RRs.Note

To configure DNS-based SSM mapping in the software, you must configure a few global commands but noper-channel specific configuration is needed. There is no change to the configuration for SSM mapping ifadditional channels are added. When DNS-based SSM mapping is configured, the mappings are handledentirely by one or more DNS servers. All DNS techniques for configuration and redundancy managementcan be applied to the entries needed for DNS-based SSM mapping.

SSM Mapping Benefits• The SSM Mapping feature provides almost the same ease of network installation and management as apure SSM solution based on IGMPv3. Some additional configuration is necessary to enable SSMmapping.

• The SSM benefit of inhibition of DoS attacks applies when SSM mapping is configured. When SSMmapping is configured the only segment of the network that may still be vulnerable to DoS attacks arereceivers on the LAN connected to the last hop router. Since those receivers may still be using IGMPv1and IGMPv2, they are vulnerable to attacks from unwanted sources on the same LAN. SSM mapping,however, does protect those receivers (and the network path leading towards them) frommulticast trafficfrom unwanted sources anywhere else in the network.

• Address assignment within a network using SSM mapping needs to be coordinated, but it does not needassignment from outside authorities, even if the content from the network is to be transited into othernetworks.

How to Configure SSM Mapping

Configuring Static SSM MappingPerform this task to configure the last hop router in an SSM deployment to use static SSMmapping to determinethe IP addresses of sources sending to groups.

Before you begin

• Enable IP multicast routing, enable PIM sparse mode, and configure SSM before performing this task.For more information, see the “Configuring Basic Multicast ”module.

• Before you configure static SSM mapping, you must configure ACLs that define the group ranges to bemapped to source addresses.

SUMMARY STEPS

1. enable

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SSM MappingSSM Mapping Benefits

2. configure terminal3. ip igmp ssm-map enable4. no ip igmp ssm-map query dns5. ip igmp ssm-map static access-list source-address6. Repeat Step 5 to configure additional static SSM mappings, if required.7. end8. show running-config9. copy running-config start-up config

DETAILED STEPS

PurposeCommand or Action

Enables privileged EXEC mode.enableStep 1

Example: Enter your password if prompted.

Device> enable

Enters global configuration mode.configure terminal

Example:

Step 2

Device# configure terminal

Enables SSM mapping for groups in the configured SSMrange.

ip igmp ssm-map enable

Example:

Step 3

By default, this command enables DNS-basedSSM mapping.

NoteDevice(config)# ip igmp ssm-map enable

(Optional) Disables DNS-based SSM mapping.no ip igmp ssm-map query dnsStep 4

Example: Disable DNS-based SSM mapping if you onlywant to rely on static SSMmapping. By default,the ip igmp ssm-map command enablesDNS-based SSM mapping.

Note

Device(config)# no ip igmp ssm-map query dns

Configures static SSM mapping.ip igmp ssm-map static access-list source-addressStep 5

Example: • The ACL supplied for the access-list argument definesthe groups to be mapped to the source IP addressentered for the source-address argument.Device(config)# ip igmp ssm-map static 11

172.16.8.11

You can configure additional static SSMmappings. If additional SSM mappings areconfigured and the router receives an IGMPv1or IGMPv2 membership report for a group inthe SSM range, the Cisco IOS XE softwaredetermines the source addresses associated withthe group by walking each configured ip igmpssm-map static command. The Cisco IOS XEsoftware associates up to 20 sources per group.

Note

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SSM MappingConfiguring Static SSM Mapping

PurposeCommand or Action

--Repeat Step 5 to configure additional static SSMmappings,if required.

Step 6

Ends the current configuration session and returns toprivileged EXEC mode.

end

Example:

Step 7

Device(config)# end

Verifies your entries.show running-config

Example:

Step 8

Device# show running-config

(Optional) Saves your entries in the configuration file.copy running-config start-up config

Example:

Step 9

Device# copy running-config start-up config

What to Do NextProceed to the Configuring DNS-Based SSM Mapping (CLI), on page 8 or to the Verifying SSM MappingConfiguration and Operation, on page 11.

Configuring DNS-Based SSM Mapping (CLI)Perform this task to configure the last hop router to perform DNS lookups to learn the IP addresses of sourcessending to a group.

Before you begin

• Enable IP multicast routing, enable PIM sparse mode, and configure SSM before performing this task.For more information, see the "Configuring Basic Multicast"module.

• Before you can configure and use SSM mapping with DNS lookups, you need to be able to add recordsto a running DNS server. If you do not already have a DNS server running, you need to install one.

SUMMARY STEPS

1. enable2. configure terminal3. ip igmp ssm-map enable4. ip igmp ssm-map query dns5. ip domain multicast domain-prefix6. ipname-server server-address1 [server-address2server-address6]7. Repeat Step 6 to configure additional DNS servers for redundancy, if required.8. end9. show running-config

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SSM MappingWhat to Do Next

10. copy running-config startup-config

DETAILED STEPS

PurposeCommand or Action

Enables privileged EXEC mode.enableStep 1

Example: Enter your password if prompted.Device# enable

Enters global configuration mode.configure terminal

Example:

Step 2

Device# configure terminal

Enables SSM mapping for groups in a configured SSMrange.

ip igmp ssm-map enable

Example:

Step 3

Device(config)# ip igmp ssm-map enable

(Optional) Enables DNS-based SSM mapping.ip igmp ssm-map query dnsStep 4

Example: • By default, the ip igmp ssm-map command enablesDNS-based SSM mapping. Only the noform of thiscommand is saved to the running configuration.

Device(config)# ip igmp ssm-map query dns

Use this command to reenable DNS-based SSMmapping if DNS-based SSM mapping isdisabled.

Note

(Optional) Changes the domain prefix used by the CiscoIOS XE software for DNS-based SSM mapping.

ip domain multicast domain-prefix

Example:

Step 5

• By default, the software uses the ip-addr.arpa domainprefix.Device(config)# ip domain multicast

ssm-map.cisco.com

Specifies the address of one or more name servers to usefor name and address resolution.

ipname-server server-address1[server-address2server-address6]

Example:

Step 6

Device(config)# ip name-server 10.48.81.21

--Repeat Step 6 to configure additional DNS servers forredundancy, if required.

Step 7

Returns to privileged EXEC mode.end

Example:

Step 8

Device(config-if)# end

Verifies your entries.show running-config

Example:

Step 9

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SSM MappingConfiguring DNS-Based SSM Mapping (CLI)

PurposeCommand or ActionDevice# show running-config

(Optional) Saves your entries in the configuration file.copy running-config startup-config

Example:

Step 10

Device# copy running-config startup-config

What to Do Next

Configuring Static Traffic Forwarding with SSM MappingPerform this task to configure static traffic forwarding with SSMmapping on the last hop router. Static trafficforwarding can be used in conjunction with SSMmapping to statically forward SSM traffic for certain groups.When static traffic forwarding with SSM mapping is configured, the last hop router uses DNS-based SSMmapping to determine the sources associated with a group. The resulting (S, G) channels are then staticallyforwarded.

SUMMARY STEPS

1. enable2. configure terminal3. interface type number4. ip igmp static-group group-address source ssm-map5. end

DETAILED STEPS

PurposeCommand or Action

Enables privileged EXEC mode.enableStep 1

Example: • Enter your password if prompted.

Device> enable

Enters global configuration mode.configure terminal

Example:

Step 2

Device# configure terminal

Selects an interface on which to statically forward trafficfor a multicast group using SSM mapping and entersinterface configuration mode.

interface type number

Example:

Device(config)# interface gigabitethernet 1/0/0

Step 3

Static forwarding of traffic with SSM mappingworks with either DNS-based SSM mapping orstatically-configured SSM mapping.

Note

Configures SSM mapping to be used to statically forwarda (S, G) channel out of the interface.

ip igmp static-group group-address source ssm-map

Example:

Step 4

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SSM MappingWhat to Do Next

PurposeCommand or Action

Device(config-if)# ip igmp static-group 232.1.2.1source ssm-map

• Use this command if you want to statically forwardSSM traffic for certain groups. Use DNS-based SSMmapping to determine the source addresses of thechannels.

Returns to privileged EXEC mode.end

Example:

Step 5

Device(config-if)# end

What to Do NextProceed to the Verifying SSM Mapping Configuration and Operation, on page 11.

Verifying SSM Mapping Configuration and OperationPerform this optional task to verify SSM mapping configuration and operation.

SUMMARY STEPS

1. enable2. show ip igmp ssm-mapping3. show ip igmp ssm-mapping group-address4. show ip igmp groups [group-name | group-address | interface-type interface-number] [detail]5. show host6. debug ip igmp group-address

DETAILED STEPS

Step 1 enable

Enables privileged EXEC mode. Enter your password if prompted.

Example:

> enable

Step 2 show ip igmp ssm-mapping

(Optional) Displays information about SSM mapping.

The following example shows how to display information about SSMmapping configuration. In this example, SSM staticmapping and DNS-based SSM mapping are enabled.

Example:

# show ip igmp ssm-mappingSSM Mapping : EnabledDNS Lookup : Enabled

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SSM MappingWhat to Do Next

Mcast domain : ssm-map.cisco.comName servers : 10.0.0.3

10.0.0.4

Step 3 show ip igmp ssm-mapping group-address

(Optional) Displays the sources that SSM mapping uses for a particular group.

The following example shows how to display information about the configured DNS-based SSMmapping. In this example,the router has used DNS-based mapping to map group 232.1.1.4 to sources 172.16.8.5 and 172.16.8.6. The timeout forthis entry is 860000 milliseconds (860 seconds).

Example:

# show ip igmp ssm-mapping 232.1.1.4Group address: 232.1.1.4Database : DNSDNS name : 4.1.1.232.ssm-map.cisco.comExpire time : 860000Source list : 172.16.8.5

: 172.16.8.6

Step 4 show ip igmp groups [group-name | group-address | interface-type interface-number] [detail]

(Optional) Displays the multicast groups with receivers that are directly connected to the router and that were learnedthrough IGMP.

The following is sample output from the show ip igmp groups command with the group-address argument and detailkeyword. In this example the “M” flag indicates that SSM mapping is configured.

Example:

# show ip igmp group 232.1.1.4 detailInterface: GigabitEthernet2/0/0Group: 232.1.1.4 SSMUptime: 00:03:20Group mode: INCLUDELast reporter: 0.0.0.0CSR Grp Exp: 00:02:59Group source list: (C - Cisco Src Report, U - URD, R - Remote,

S - Static, M - SSM Mapping)Source Address Uptime v3 Exp CSR Exp Fwd Flags172.16.8.3 00:03:20 stopped 00:02:59 Yes CM172.16.8.4 00:03:20 stopped 00:02:59 Yes CM172.16.8.5 00:03:20 stopped 00:02:59 Yes CM172.16.8.6 00:03:20 stopped 00:02:59 Yes CM

Step 5 show host

(Optional) Displays the default domain name, the style of name lookup service, a list of name server hosts, and the cachedlist of hostnames and addresses.

The following is sample output from the show hostcommand. Use this command to display DNS entries as they arelearned by the router.

Example:

# show hostDefault domain is cisco.comName/address lookup uses domain serviceName servers are 10.48.81.21Codes: UN - unknown, EX - expired, OK - OK, ?? - revalidate

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SSM MappingVerifying SSM Mapping Configuration and Operation

temp - temporary, perm - permanentNA - Not Applicable None - Not defined

Host Port Flags Age Type Address(es)10.0.0.0.ssm-map.cisco.c None (temp, OK) 0 IP 172.16.8.5

172.16.8.6172.16.8.3

172.16.8.4

Step 6 debug ip igmp group-address

(Optional) Displays the IGMP packets received and sent and IGMP host-related events.

The following is sample output from the debug ip igmpcommand when SSM static mapping is enabled. The followingoutput indicates that the router is converting an IGMPv2 join for group G into an IGMPv3 join:

Example:

IGMP(0): Convert IGMPv2 report (*,232.1.2.3) to IGMPv3 with 2 source(s) using STATIC.

The following is sample output from the debug ip igmp command when DNS-based SSM mapping is enabled. Thefollowing output indicates that a DNS lookup has succeeded:

Example:

IGMP(0): Convert IGMPv2 report (*,232.1.2.3) to IGMPv3 with 2 source(s) using DNS.

The following is sample output from the debug ip igmp command when DNS-based SSM mapping is enabled and aDNS lookup has failed:

IGMP(0): DNS source lookup failed for (*, 232.1.2.3), IGMPv2 report failed

Configuration Examples for SSM Mapping

SSM Mapping ExampleThe following configuration example shows a router configuration for SSM mapping. This example alsodisplays a range of other IGMP and SSM configuration options to show compatibility between features. Donot use this configuration example as a model unless you understand all of the features used in the example.

Address assignment in the global SSM range 232.0.0.0/8 should be random. If you copy parts or all of thissample configuration, make sure to select a random address range but not 232.1.1.x as shown in this example.Using a random address range minimizes the possibility of address collision and may prevent conflicts whenother SSM content is imported while SSM mapping is used.

Note

!no ip domain lookupip domain multicast ssm.map.cisco.comip name-server 10.48.81.21!!

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SSM MappingConfiguration Examples for SSM Mapping

ip multicast-routing distributedip igmp ssm-map enableip igmp ssm-map static 10 172.16.8.10ip igmp ssm-map static 11 172.16.8.11!!...!interface GigabitEthernet0/0/0description Sample IGMP Interface Configuration for SSM-Mapping Exampleip address 10.20.1.2 255.0.0.0ip pim sparse-modeip igmp last-member-query-interval 100ip igmp static-group 232.1.2.1 source ssm-mapip igmp version 3ip igmp explicit-trackingip igmp limit 2ip igmp v3liteip urd!...!ip pim ssm default!access-list 10 permit 232.1.2.10access-list 11 permit 232.1.2.0 0.0.0.255!

This table describes the significant commands shown in the SSM mapping configuration example.

Table 1: SSM Mapping Configuration Example Command Descriptions

DescriptionCommand

Disables IP DNS-based hostname-to-address translation.

The no ip domain-list command is shown in the configurationonly to demonstrate that disabling IP DNS-basedhostname-to-address translation does not conflict withconfiguring SSM mapping. If this command is enabled, theCisco IOS XE software will try to resolve unknown strings ashostnames.

Note

no ip domain lookup

Specifies ssm-map.cisco.com as the domain prefix for SSM mapping.ip domain multicastssm-map.cisco.com

Specifies 10.48.81.21 as the IP address of the DNS server to be used bySSM mapping and any other service in the software that utilizes DNS.

ip name-server 10.48.81.21

Enables IP multicast routing.ip multicast-routing

Enables SSM mapping.ip igmp ssm-map enable

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SSM MappingSSM Mapping Example

DescriptionCommand

Configures the groups permitted by ACL 10 to use source address172.16.8.10.

• In this example, ACL 10 permits all groups in the 232.1.2.0/25 rangeexcept 232.1.2.10.

ip igmp ssm-map static 10172.16.8.10

Configures the groups permitted by ACL 11 to use source address172.16.8.11.

• In this example, ACL 11 permits group 232.1.2.10.

ip igmp ssm-map static 11172.16.8.11

Enables PIM sparse mode.ip pim sparse-mode

Reduces the leave latency for IGMPv2 hosts.

This command is not required for configuring SSM mapping;however, configuring this command can be beneficial forIGMPv2 hosts relying on SSM mapping.

Note

ip igmplast-member-query-interval 100

Configures SSM mapping to be used to determine the sources associatedwith group 232.1.2.1. The resulting (S, G) channels are staticallyforwarded.

ip igmp static-group 232.1.2.1source ssm-map

Enables IGMPv3 on this interface.

This command is shown in the configuration only todemonstrate that IGMPv3 can be configured simultaneouslywith SSM mapping; however, it is not required.

Note

ip igmp version 3

Minimizes the leave latency for IGMPv3 host leaving a multicast channel.

This command is not required for configuring SSM mapping.Note

ip igmp explicit-tracking

Limits the number of IGMP states resulting from IGMPmembership stateson a per-interface basis.

This command is not required for configuring SSM mapping.Note

ip igmp limit 2

Enables the acceptance and processing of IGMP v3lite membership reportson this interface.

This command is shown in the configuration only todemonstrate that IGMP v3lite can be configured simultaneouslywith SSM mapping; however, it is not required.

Note

ip igmp v3lite

Enables interception of TCP packets sent to the reserved URD port 465on an interface and processing of URD channel subscription reports.

This command is shown in the configuration only todemonstrate that URD can be configured simultaneously withSSM mapping; however, it is not required.

Note

ip urd

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SSM MappingSSM Mapping Example

DescriptionCommand

Configures SSM service.

The default keyword defines the SSM range access list as 232/8.

ip pim ssm default

Configures the ACLs to be used for static SSM mapping.

These are the ACLs that are referenced by the ip igmpssm-map static commands in this configuration example.

Note

access-list 10 permit 232.1.2.10access-list 11 permit 232.1.2.00.0.0.255

DNS Server Configuration ExampleTo configure DNS-based SSM mapping, you need to create a DNS server zone or add records to an existingzone. If the routers that are using DNS-based SSM mapping are also using DNS for other purposes besidesSSM mapping, you should use a normally-configured DNS server. If DNS-based SSM mapping is the onlyDNS implementation being used on the router, you can configure a fake DNS setup with an empty root zone,or a root zone that points back to itself.

The following example shows how to create a zone and import the zone data using Network Registrar:

Router> zone 1.1.232.ssm-map.cisco.com. create primary file=named.ssm-map100 OkRouter> dns reload100 Ok

The following example shows how to import the zone files from a named.conf file for BIND 8:

Router> ::import named.conf /etc/named.confRouter> dns reload100 Ok:

Network Registrar version 8.0 and later support import BIND 8 format definitions.Note

Additional ReferencesRelated Documents

Document TitleRelated Topic

Cisco IOSMaster Commands List, All ReleasesCisco IOS commands

Standards and RFCs

TitleStandard/RFC

—No specific Standards and RFCs are supported by the features in this document.

SSM Mapping16

SSM MappingDNS Server Configuration Example

MIBs

MIBs LinkMIB

To locate and download MIBs for selected platforms, Cisco IOS releases, and feature sets, use CiscoMIB Locator found at the following URL:

http://www.cisco.com/go/mibs

—

Technical Assistance

LinkDescription

http://www.cisco.com/supportThe Cisco Support website provides extensive online resources, includingdocumentation and tools for troubleshooting and resolving technical issueswith Cisco products and technologies.

To receive security and technical information about your products, you cansubscribe to various services, such as the Product Alert Tool (accessed fromField Notices), the Cisco Technical Services Newsletter, and Really SimpleSyndication (RSS) Feeds.

Access to most tools on the Cisco Support website requires a Cisco.com userID and password.

Feature Information for SSM MappingThe following table provides release information about the feature or features described in this module. Thistable lists only the software release that introduced support for a given feature in a given software releasetrain. Unless noted otherwise, subsequent releases of that software release train also support that feature.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support.To access Cisco Feature Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required.

Table 2: Feature Information for SSM Mapping

Feature InformationReleasesFeature Name

This feature was introduced on the Cisco ASR 920 SeriesAggregation Services Router (ASR-920-12CZ-A,ASR-920-12CZ-D, ASR-920-4SZ-A, ASR-920-4SZ-D,ASR-920-10SZ-PD, ASR-920-24SZ-IM, ASR-920-24SZ-M,ASR-920-24TZ-M) .

Cisco IOS XE Release3.14.0S

SSMMapping

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SSM MappingFeature Information for SSM Mapping

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SSM MappingFeature Information for SSM Mapping